Low sulfur fuel oil from high metals containing petroleum residuum

ABSTRACT

The production of low sulfur fuel oil from a high metals containing Venezuelan petroleum residuum is improved when the reaction zone is operated with 40 to 60 volume percent of a high surface area demetalization material and a 40 to 60 volume percent of a high activity hydrogenation catalyst with a limited porosity. Such an operation results in enhanced demetalization without a reduction in the desulfurization.

United States Patent 1191 Wolk et a1. June 25, 1974 LOW SULFUR FUEL OIL FROM HIGH 3,183,178 5/1965 Wolk 208/58 METALS CONTAINING PETROLEUM 3,496,099 2/1970 Bridge 208/251 RESIDUUM 3,573,201 3/1971 Anncsscr et a1. 3,705,350 12/1972 Wolk 208/127 Inventors: Ronald H. Wolk, Trenton, N..l.;

William C. Rovesti, Levittown, Pa.

Assignee: Hydrocarbon Research, Inc., New

York, NY.

Filed: Nov. 26, 1971 Appl. No.: 202,413

US. Cl. 208/216, 208/251 H 1m. (:1. Cl0g 23/02 Field of Search 208/216, 251 H References Cited UNITED STATES PATENTS 12/1959 Ashley 208/213 Solids Removal Primary Examiner-Delbert E. Gantz Assistant Examiner-S. Berger 7 [5 7] ABSTRACT The production of low sulfur fuel oil from a high metals containing Venezuelan petroleum residuum is improved when the reaction zone is operated with 40 to 60 volume percent of a high surface area demetalization material and a 40 to 60 volume percent of a high activity hydrogenation catalyst with a limited porosity. Such an operation results in enhanced demetalization without a reduction in the desulfurization.

5 Claims, 2 Drawing Figures Liquid and Gas Removol Solids Addition Hydrogen PATfiNTEnJlmeslsn Solids Removal Liquid and Gus Removal Sohds Mixture FIG. I

2 v Oil }Solids Addition Hydrogen Single Mixed Bed Two Seporote c Beds I l l 20 3O 4O 5O 6O 7O 8O 90 Percent Desulfurimflon LOW SULFUR FUEL OIL FROM HIGH METALS CONTAINING PETROLEUM RESIDUUM BACKGROUND OF THE INVENTION The upgrading of petroleum residua obtained from the refining of high metals content crudes, such as Venezuelan crude, is difficult especially when a low sulfur fuel oil is desirable. The presence of the metals, such as nickel and vanadium has proved to be detrimental to the upgrading as the metals cause a rapid deactivation of the catalysts used. It has heretofore been advantageous to upgrade such petroleum residua by operating a first stage zone for demetalization and a second stage zone for desulfurization. In this way, the high activity low porosity desulfurization catalyst is not exposed to the initial high metals content of the residuum.

Metallic contaminants are found to exist in petroleum residua in a variety of forms. They are generally present as organo-metallic compounds of relatively high molecular weight such as metallic porphyrins. These organo-metallic complexes are basically found in the asphaltenic material in the crude petroleum. As the crude is refined, the asphaltenes and, therefore, the metals become concentrated in the residua.

Whereas it is normally easy for the high activity low porosity catalysts to reduce the sulfur or nitrogen or oxygenated compound content in residua, the presence of large quantities of asphaltenic material and organometallic compounds in Venezuelan residua interferes considerably with the catalyst activity thereby limiting the levels of reduction in impurities. The prior art has sought to remedy this problem by other means of metals removal from the residua, such as by using propane deasphalting followed by thermal cracking or coking,

'desalting followed by halogen hydride treatment for coagulation, multiple bed catalytic liquid phase hydrogenation and catalytic vapor phase hydro-cracking such as set forth in US. Pat. Nos. 3,530,062; 2,951,035; 2,902,429 and 2,89 l ,005.

The present attention being given air pollution standards has greatly limited the number of fuels which may now be consumed. This has made the production of low sulfur fuels a primary concern of the petroleum industry. The high metals content of the Venezuelan crudes makes it difficult to subsequently treat the resulting residua for the production of a low sulfur fuel oil. Additionally, it is desirable to reach the lowest levels of metals content for the required level of sulfur. This desire for combined minimization of metals and sulfur requires the use of two different catalysts. The demetalization rate is low in comparison to the desulfurization rate and, therefore, the first stage demetalization zone has had to be of a larger size than the desulfurization zone. These problems in desulfurizing Venezuelan residua have greatly hindered their suitability for providing low sulfur fuel oils.

SUMMARY The 33 to 84 percent desulfurization of a Venezuelan residuum has been obtained with minimum deactivation of the desulfurization catalyst. It has been discovered that the order in which the solid demetalization agent and the desulfurization catalyst are placed becomes critical to the extent of demetalization in terms of vanadium removal from a residuum. More particularly, it was discovered that the vanadium content of the fuel oil product is most significantly decreased per unit desulfurization over the operation wherein the demetalization occurred in a separate stage. Furthermore, the deactivation of the catalyst (reduction of the amount of desulfurization with increasing catalyst age) was not detrimentally affected when the two solids were mixed.

DESCRIPTION OF THE DRAWING FIG. 1 shows a generalized reactor system with a combined particulate solids bed of porous demetalization solids and low porosity, high activity, solid desulfurization catalyst wherein the petroleum residuum and hydrogen are continuously added while the products undergo continuous removal.

FIG. 2 is a graph comparing the effect of the use of separate reaction zones for the demetalization and desulfurization of a residuum against the use of a combined demetalization-desulfurization reaction zone.

DESCRIPTION OF PREFERRED EMBODIMENT The preferred embodiment of this invention is a hydrodesulfurization reactor system wherein a liquid phase reaction is carried out in the presence of a reactant gas and a mixture of a porous demetalization contact solid and a high activity desulfurization catalyst having a limited porosity. This invention is not limited to one type of reactor system. It allows the use of any system which may be devised such that the liquid phase and reactant gas phase are in contact with the two, intimately mixed solids.

A liquid hydrocarbon oil in 2 and a hydrogen rich stream, 4, containing at least 50 percent hydrogen may be fed as a combined feed in 6 and pass to reaction zone 12. The hydrocarbon oil is preferably a high sulfur high metals containing residuum having at least 50 ppm vanadium and most preferably at least ppm vanadium such as a Venezuelan light or heavy atmospheric residuum.

The reaction zone 12 is operated at a temperature in the range of 700to 850F and a pressure between 1,000 and 3,000 psig.

Demetalization, in 10, and desulfurization, in 8, particulate solids are fed to reaction zone 12. These particles preferably have the same fluidizing properties which thereby insures that they are intimately mixed in the reaction zone 12 and they may be extrudates as well as random shaped. These particulate solids may be fed continuously or intermittently in 10 and 8 amd may similarly be removed in 16, unless a fixed bed is used.

The demetalization particulate solids are preferably a porous material which may be promoted and having a surface area of at least 100 m /g such as activated bauxite or alumina. The desulfurization particulate solids are preferably a high active hydrodesulfurization catalyst which has a limited porosity on the order of a maximum pore volume of 0.05 cc/g in pores of diameter equal to or greater than A as determined by a mercury porosimeter measurement, such as cobalt molybdate on alumina.

The porous demetalization solid is primarily designed to remove vandium from the feed and desulfurization is mainly accomplished by contacting the feed in 2 with the desulfurization catalyst in the presence of hydrogen from 4 under conditions to effect a desulfurization of 33 to 84 percent removal in the product leaving in 18. The contacting of the liquid feed with the mixture of the two solids in the presence of hydrogen in one single zone, FIG. 2, line 20, enhances the removal of vanadium from the feed during the desulfurization operation. This is most apparent when compared, as in FIG. 2 line 30, to the situation where the same proportion of porous demetalization solid and high activity desulfurization catalyst of limited porosity is used, but the demetalization takes place in a first zone and the desulfurization takes place in a second zone such that the two solids are not mixed. Furthermore, this enhance ment of vanadium removal occurs without the deactivation rate of the desulfurization catalyst (as defined by the reduction in amount of desulfurization with increasing catalyst age) being detrimentally effected for the two cases compared above. The use of a porous demetalization solid whether it preceeds or is mixed with the desulfurization catalyst enhances the life of the desulfurization catalyst as compared to the case where no demetalization solid is used. The mixing of the two solids, as described in this invention, retains the advantage of protecting the life of the desulfurization catalyst while offering enhanced vanadium removal, both results being unexpected.

The effectiveness of this invention is more fully disclosed in the following explanation of Examples I and ll which are based on operating results.

EXAMPLE I DEMETALIZATION AND DESULFURlZATlON OF VENEZUELA HEAVY ATMOSPHERIC RESIDUUM- Feed: Venezuela Heavy Atmospheric Residuum 12 APl 400 ppm Vanadium 65 ppm Nickel Arrangement of Catalyst and Porous Demetalization Agent Demetalization Agent Demetalization Agent lntimately Mixed Preceeding Catalyst With Catalyst Catalyst '/r /1 7( Age Demetal- Desulfur- Demetal- Desulfur- Bhl/lh* ization ization ization ization Catalyst: Cobalt Molybdate on Alumina l/32"Extrudates Demetalization Agent: Activated Bauxite l-20 Mesh Barrels of oil treated per pound of catalyst used.

EXAMPLE [I DEMETALlZATlON AND DESULFURIZATION OF VENEZUELA LIGHT ATMOSPHERIC RESIDUUM Again an enhanced demetalization is effected, as shown in Example II, when this same desulfurization catalyst is mixed with a l l 6 inch porous extrudate having an alumina content of 95 percent with the remainder being mainly silica. In this case the petroleum oil used was Venezuela light atmospheric residuum having half the vanadium content of the Venezuela heavy atmospheric resid. In both of these examples it can be seen that this enhanced demetalization occurs over a wide range of desulfurization levels, beginning as low as 33 percent and extending up to 84 percent sulfur removal.

Although the detailed mechanism of this enhanced demetalization has not been established, the improvement inherent in this invention is probably due to the reaction of the vanadium laden asphaltenic molecules in the presence of the desulfurization catalyst whereby they are transformed in such a way that the porous demetalization solid, in intimate contact with the catalyst, can readily remove the vanadium from the reaction liquid and does so in preference to the vanadium, in the feed or as transformed, deactivating the desulfurization catalyst. in the case where the porous demetalization solid precedes the catalyst, the only vanadium that is removed is in that form which doesnt require the further action of the hydrogenation components on the catalyst.

We claim:

1. A process for the production of low sulfur fuel oil from hydrocarbon residua having a high metals content of at least 50 ppm of vanadium wherein said residua is contacted under reaction conditions of temperature in the range of 700 to 850F and pressures in the range of 1,000 to 3,000 psig with hydrogen in the presence of a particulate solids bed, the improvement which comprises forming said bed of an intimate admixture of an inert demetalization solids having high porosity, a surface area of at least m'/ g and low activity and a desulfurization catalytic solids of low porosity with a maximum pore volume of 0.5 cc/g in pores of diameters equal to or greater than A and having a high activity, said demetalization solids and said catalytic solids having substantially the same fluidizing properties.

2. The process of claim 1 wherein said demetalization solids are selected from the group consisting of activated bauxite, alumina, silica and combinations thereof.

3. The process of claim 1 wherein said desulfurization catalyst is cobalt molybdate on alumina.

4. The process of claim 1 wherein said demetalization and said desulfurization solids are present in a ratio between about 2:3 to 3:2.

5. A process for the production of low sulfur fuel oil from hydrocarbon residua having a high metals content of at least 50 ppm of vanadium wherein the residua and hydrogen pass upwardly through a particulate solids porosity, a surface area of at least m /g and low activity and a desulfurization catalytic solids of low porosity with a maximum pore volume of 0.5 cc/g in pores of diameters equal to or greater than A and having a high activity, said demetalization solids and said catalytic solids having substantially the same fluidizing properties. 

2. The process of claim 1 wherein said demetalization solids are selected from the group consisting of activated bauxite, alumina, silica and combinations thereof.
 3. The process of claim 1 wherein said desulfurization catalyst is cobalt molybdate on alumina.
 4. The process of claim 1 wherein said demetalization and said desulfurization solids are present in a ratio between about 2:3 to 3:2.
 5. A process for the production of low sulfur fuel oil from hydrocarbon residua having a high metals content of at least 50 ppm of vanadium wherein the residua and hydrogen pass upwardly through a particulate solids bed under ebullating bed conditions and wherein said residua is contacted under reaction conditions of temperatures in the range of 700* to 850*F and pressures in the range of 1,000 to 3,000 psig with hydrogen in the presence of said particulate solids bed, the improvement which comprises forming said bed of an intimate admixture of an inert demetalization solids having high porosity, a surface area of at least 100 m2/g and low activity and a desulfurization catalytic solids of low porosity with a maximum pore volume of 0.5 cc/g in pores of diameters equal to or greater than 120A and having a high activity, said demetalization solids and said catalytic solids having substantially the same fluidizing properties. 